For the purpose of protecting against damage due to an overimposed current, etc., a semiconductor device is provided with an electric current detection region to detect electric current flowing through the semiconductor device. Japanese Patent Application Publication No. H7-245394 discloses a semiconductor device having a main active region (main cell region) in which an IGBT is formed, and an electric current detection region (detector cell region) for detecting electric current that flows through the main active region provided in one semiconductor substrate. An IGBT identical to that on the main active region is formed in the electric current detection region, and the electric current detection region is spaced apart from the main active region by 100 μm or more. In this configuration, carrier interference at the boundary region between the electric current detection region and the main active region is prevented, and the electric current ratio between the main electric current flowing through the main active region and the detected electric current flowing through the electric current detection region is maintained substantially constant.